菜鸟问个简单的逻辑问题，求解答

function dwz($id,$str=""){	$a=array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");	$zs=(int)($id/sizeof($a));	$xs=$id%sizeof($a);	if($zs>=sizeof($a)){		$str=$a[$xs].$str;		dwz($zs,$str);	}	else{		if($str==""){			return $a[$zs].$a[$xs];		}		else{			echo   $a[$zs].$str;//这里只能

回复讨论(解决方案)

第7行 dwz($zs,$str);
没有承接返回
$str = dwz($zs,$str);

函数结束处还需要有 return $str;

    if($zs>=sizeof($a)){         $str=$a[$xs].$str;         dwz($zs,$str); //这里加入return： return dwz($zs, $str);    } 

第7行 dwz($zs,$str);
没有承接返回
$str = dwz($zs,$str);

函数结束处还需要有 return $str;

哈哈，可以啦，谢谢你的提醒和指导

这样写也可以，可逆的前不限长度

echo convert_62(999990); //4C8secho convert_62('4C8s', 1); //999990function convert_62($s, $mode=0) {  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');  $r = '';  if($mode) {    $d = array_flip($d);    for($i=0; $i 
 
  这样写也可以，可逆的前不限长度  
echo convert_62(999990); //4C8secho convert_62('4C8s', 1); //999990function convert_62($s, $mode=0) {  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');  $r = '';  if($mode) {    $d = array_flip($d);    for($i=0; $i  
 受用了，谢谢你 
 
  这样写也可以，可逆的前不限长度  
echo convert_62(999990); //4C8secho convert_62('4C8s', 1); //999990function convert_62($s, $mode=0) {  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');  $r = '';  if($mode) {    $d = array_flip($d);    for($i=0; $i  
  
 不好意思，请问下为什么我把这个文件放在本地测试可以用，但是放在服务器上不能用，会提示找不到bcmod这个函数 
 
  嗯，这是 php_bc 扩展没加载的原因（php for win 是自动加载的）  
 你还可以检查一下 php_gmp 扩展是否已加载，用这个函数库也是一样的 
 
  嗯，这是 php_bc 扩展没加载的原因（php for win 是自动加载的）  
 你还可以检查一下 php_gmp 扩展是否已加载，用这个函数库也是一样的  
  
 真的没有加载，那怎么办啊？  
 我没服务器的权限 
 
  print_r(get_loaded_extensions());  
 看看都有些什么 
 
  print_r(get_loaded_extensions());  
 看看都有些什么  
  
  
Array(    [0] => date    [1] => libxml    [2] => openssl    [3] => pcre    [4] => zlib    [5] => ctype    [6] => curl    [7] => dom    [8] => filter    [9] => ftp    [10] => gd    [11] => hash    [12] => iconv    [13] => json    [14] => mbstring    [15] => mcrypt    [16] => mhash    [17] => mysql    [18] => SimpleXML    [19] => SPL    [20] => PDO    [21] => posix    [22] => Reflection    [23] => session    [24] => pdo_sqlite    [25] => sockets    [26] => SQLite    [27] => standard    [28] => tokenizer    [29] => xml    [30] => xmlreader    [31] => xmlwriter    [32] => zip    [33] => apache2handler    [34] => memcache    [35] => mssql    [36] => soap    [37] => Zend Optimizer)
 
 
  没权限就不好办了  
 就自己写吧，你不是也写了吗 
 
  没权限就不好办了  
 就自己写吧，你不是也写了吗  
  
 我写的那个有错，发现运算到后面就错了，然后就用了你的  
 还是没搞清楚我的那个错在哪里，为什么运算到后面就错了  
 大神，帮忙看下吧 
 
  
function dwz($id,$str=""){$a=array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");	$zs=(int)($id/sizeof($a));	$xs=$id%sizeof($a);	if($zs>=sizeof($a)){		$str=$a[$xs].$str;		$str=dwz($zs,$str);	}	else{		if($str==""){return $a[$zs].$a[$xs];}		else{return $a[$zs].$str;}	}	return $str;}
  
  
 这是我根据你的提示改的，可以显示出来，但是我之前的算法有错，帮忙看下 
 
  终于可以了，谢谢大神  
  
function dwz($s) {  $d = str_split('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVEXYZ');  $r = '';  while($s) {	$r = $d[(int)($s%62)].$r;	$s = (int)($s/62);  }  return $r;}